N6‐methyladenosine‐mediated upregulation of LNCAROD confers radioresistance in esophageal squamous cell carcinoma through stabilizing PARP1

Abstract Background Radiotherapy is a primary therapeutic modality for esophageal squamous cell carcinoma (ESCC), but its effectiveness is still restricted due to the resistance of cancer cells to radiation. Long non‐coding RNAs (lncRNAs) and N 6 ‐methyladenosine (m6A) have been shown to play significant roles in tumour radioresistance. However, the precise manifestation and role of m6A‐modified lncRNAs in ESCC radioresistance remain unclear. Methods Bioinformatics analysis was conducted to identify m6A‐modified lncRNAs implicated in the radioresistance of ESCC. A series of functional experiments were performed to investigate the function of LNCAROD in ESCC. Methylated RNA immunoprecipitation, chromatin isolation by RNA purification‐mass spectrometry, RNA immunoprecipitation, and co‐immunoprecipitation experiments were performed to explore the mechanism of m6A‐mediated upregulation of LNCAROD expression and the downstream mechanism enhancing the radioresistance of ESCC. The efficacy of LNCAROD in vivo was assessed using murine xenograft models. Results Herein, we identified LNCAROD as a novel METTL3‐mediated lncRNA that enhanced radioresistance in ESCC cells and was post‐transcriptionally stabilised by YTHDC1. Moreover, we confirmed that LNCAROD prevented ubiquitin‐proteasome degradation of PARP1 protein by facilitating PARP1‐NPM1 interaction, thereby contributing to homologous recombination‐mediated DNA double‐strand breaks repair and enhancing the radiation resistance of ESCC cells. Silencing LNCAROD in a nude mouse model of ESCC in vivo resulted in slower tumour growth and increased radiosensitivity. Conclusion Our findings enhance the understanding of m6A‐modified lncRNA‐driven machinery in ESCC radioresistance and underscore the significance of LNCAROD in this context, thereby contributing to the development of a potential therapeutic target for ESCC patients.